First New Hepatitis E Vaccine Shown 96 Percent Effective
Hepatitis E is similar to hepatitis A.Mild cases of hepatitis A don't require treatment, and most people who are infected recover completely with no permanent liver damage. Unlike hepatitis B and C, hepatitis A doesn't develop into chronic hepatitis or cirrhosis — both potentially fatal conditions.In general, hepatitis E is a self-limiting viral infection followed by recovery. Prolonged viraemia or faecal shedding are unusual and chronic infection does not occur.
Since cases of hepatitis E are not clinically distinguishable from other types of acute viral hepatitis, diagnosis is made by blood tests which detect elevated antibody levels of specific antibodies to hepatitis E in the body or by reverse transcriptase polymerase chain reaction (RT-PCR). Unfortunately, such tests are not widely available.
It is less common than hepatitis A. Hepatitis E is most common in poorly developed countries and rarely seen in the United States.Hepatitis E should be suspected in outbreaks of waterborne hepatitis occurring in developing countries, especially if the disease is more severe in pregnant women, or if hepatitis A has been excluded. If laboratory tests are not available, epidemiologic evidence can help in establishing a diagnosis.
Hepatitis E is an acute viral hepatitis (liver inflammation) caused by infection with a virus called hepatitis E virus (HEV). HEV is transmitted via the faecal-oral route. Hepatitis E is a waterborne disease, and contaminated water or food supplies have been implicated in major outbreaks. Consumption of faecally contaminated drinking water has given rise to epidemics, and the ingestion of raw or uncooked shellfish has been the source of sporadic cases in endemic areas. There is a possibility of zoonotic spread of the virus, since several non-human primates, pigs, cows, sheep, goats and rodents are susceptible to infection. The risk factors for HEV infection are related poor sanitation in large areas of the world, and HEV shedding in faeces.
Person-to-person transmission is uncommon. There is no evidence for sexual transmission or for transmission by transfusion.
A new vaccine may safely protect against hepatitis E, a virus prevalent in developing countries.
In a study of 2,000 healthy adults from Nepal, researchers found that the vaccine was 96 percent effective in preventing hepatitis E infection.
"This is the first new hepatitis vaccine strain for which efficacy has been shown since 1992, and it's very well tolerated. I would say this vaccine is a home run," said the study's lead author, Dr. Bruce Innis, vice president of clinical research and development for GlaxoSmithKline, the vaccine's manufacturer.
Hepatitis E is an infectious disease that's generally spread through fecal contamination of food or water, according to the World Health Organization (WHO). It's often a self-limiting illness, and most people recover with no long-term consequences. However, women in their third trimester of pregnancy are particularly susceptible to hepatitis E and have a mortality rate as high as 20 percent from the infection.
The hepatitis E virus is relatively uncommon in the United States but is prevalent in other areas of the world. According to background information in the study, it's estimated that as many as one-third of the world's population has been infected with hepatitis E. And, in some countries, such as India, that rate may be as high as 60 percent.
Symptoms of hepatitis E develop from three to eight weeks after exposure, with an average incubation period of 40 days, according to WHO. Those most at risk include people between the ages of 15 and 40, pregnant women and people traveling to countries where hepatitis E is common, according to the U.S. Centers for Disease Control and Prevention. Symptoms of the disease include jaundice, abdominal pain, fatigue, loss of appetite, dark urine, nausea and vomiting.
To test the efficacy of the newly developed recombinant vaccine, 2,000 healthy adults -- 99.6 percent of them male -- from Nepal were randomly selected to receive either the vaccine or a placebo shot. All of the study volunteers were part of the Nepalese army.
The vaccine was administered in three doses, with the second dose given after a month and the third given at six months. The average follow-up time was 804 days. Innis said that political turmoil in Nepal added to the challenge of conducting a study in a country where there is little industrial development.
At the end of the study, complete follow-up data was available on 1,794 study volunteers -- 898 who received the vaccine and 896 from the placebo group.
Hepatitis E developed in 69 people during the study period. Sixty-six of those infected were from the placebo group.
The vaccine's efficacy was 95.5 percent, according to the study.
Innis said the researchers were surprised by the high rates of hepatitis E infection. "We knew that there was a good amount of hepatitis E in this population, but the incidence of disease in the placebo group was about twice as high as we anticipated it would be," he said. "By immunizing against hepatitis E -- an orphan disease -- we had a substantial impact on the well-being of those vaccinated. We do believe this is a product that could relieve a great deal of human suffering."
Liver specialist Dr. Tusar Desai, of William Beaumont Hospital in Royal Oak, Mich., said the study's findings are "exciting." He said he wasn't concerned that the study was done mostly with men, because men and women tend to react similarly to vaccines.
What is a concern, Desai said, is that the researchers conducted the study with soldiers, who tend to be thin. And, he said, there is a difference in the way thin and overweight people process immunizations -- vaccines aren't as effective in people who carry extra weight.
Still, Desai said, when this vaccine becomes available, he would recommend it to anyone in the United States who was traveling to an area of the world where hepatitis E is endemic.
It's still not clear when the vaccine might become available.
Innis said GlaxoSmithKline is looking for public or private partnerships to "share with us some of the risk of carrying the development of this vaccine forward."
Improving sanitation is the most important measure, which consists in proper treatment and disposal of human waste, higher standards for public water supplies, improved personal hygiene procedures and sanitary food preparation. Practicing good hygiene — including washing your hands often — is one of the best ways to protect against hepatitis A. Effective vaccines are available for people who are most at risk.
- Travelers to developing countries, particularly in South Asia and North Africa
- Rare cases have occurred in the United States among persons with no history of travel to endemic countries.